Ch. 3.3

Question 1

atomic number

Answer 1

• the number of protons
• determines type of element
• DOESN’T VARY

Question 2

atomic mass units

Answer 2

a new unit created for measuring the mass of an atom
*amu

Question 3

1 amu is how many grams?

Answer 3

1.7 x 10*-24 g

Question 4

1 proton is how many grams?

Answer 4

1.673 x 10*-24 g

Question 5

1 neutron is how many grams?

Answer 5

1.675 x 10*-24 g

Question 6

1 electron is how much in amu?

Answer 6

0.00054 amu

Question 7

atomic mass

Answer 7

is the mass of a single atom
*EX. 4amu + 5amu + .00216 amu = 9.00216 amu

Question 8

mass number

Answer 8

the total number of protons and neutrons that make up the nucleus of an atom
*like an approximation
*EX. 4p + 5n + 4e = 9 amu

Question 9

isotopes

Answer 9

is different versions of the same element
*different # of neutrons
*different masses
*elements have multiple isotopes

Question 10

two ways in naming isotopes:

Answer 10

Hyphen notation
Nuclear symbol notation

Question 11

hyphen notation

Answer 11

• is when the mass number is written with a hyphen after the name of the element

Question 12

nuclear symbol notation

Answer 12

• is where the subscript indicates the mass number and the subscript indicates the atomic number
  *Mass number on top
  *Atomic number on bottom

Question 13

average atomic mass (molar mass)

Answer 13

is the weighted average of the atomic masses of the naturally occurring isotopes of an element
*what is listed on periodic table

Question 14

how to calculate average atomic mass:

Answer 14

mass # of isotopes A x % abundance
mass # of isotopes B x % abundance
mass # of isotopes C x % abundance +
——————————————
Average atomic mass

Question 15

One electron ALMOST ALWAYS equals one what?

Answer 15

1 proton

Question 16

1 proton and 1 neutron is how much in amu?

Answer 16

Both equal 1 amu

Question 17

Uranium-235

Answer 17

Element - mass number